The pathways of physiology provide systems of genes that link genetic variation and divergence to whole-organism physiological performance traits, such as development rate, metabolic rate, flight velocity, ethanol tolerance and stress responses. Our research integrates experimental, comparative, quantitative genetic, population genetic/genomic, bioinformatic and classical genetic approaches to link genes to their evolutionarily and ecologically significant function.

Drosophila have a unique ecology, acquiring nutrient resources in habitats ranging from desert cactus rots to ethanol-rich vineyards and using these resources to fuel metabolism during energetically challenging feats, such as larval development and locomotion and adult flight. D. melanogaster also has an interesting natural history, expanding its ancestral range out of the tropics of Africa to inhabit temperate latitudes that experience colder and more variable temperatures. At the same time, these cosmopolitan flies evolved extraordinary ethanol tolerance to exploit a habitat rich in the products of fermentation. We are interested in how this natural history and ecology has led to divergence and plasticity in the pathways that mediate environmental temperature and ethanol.

Drosophila allow us to test predictions from evolutionary theory and from models of physiological ecology in a genetic context, but our approach is not limited to working with this model organism. Members of the lab are encouraged to choose study organisms based on the investigation of physiological adaptations that offer insight into the evolutionary forces shaping genetic and phenotypic variation within and divergence among natural populations.

Physiological systems within which we study the mechanisms of evolution:

Cellular, physiological and behavioral adaptations to a variable environment

The tremendous diversity in form and function across the Tree of Life is matched by an equally amazing diversity of cellular, physiological and behavioral adaptations that enable organisms to function in their environments. We investigate the genetic bases for plastic and fixed adaptive strategies, including how embryos defend themselves against thermal stress (Dr. Brent Lockwood), how mom's preferences and her mRNAs might buffer this stress, how cellular plasticity evolves (Brandon Cooper) and how pathways that mediate thermal stress (Luke Hoekstra, Robert Kobey) and ethanol tolerance diverge among natural populations across latitudes.

Causes and consequences of mitochondrial-nuclear coevolution

The unique genetics of the mtDNA are thought to drive compensatory and positive coevolution in nuclear genes. We explore the drivers of this coevolution using population genetic and molecular evolutionary analysis of patterns of mitochondrial mutation and substitution, as well as genetic manipulations to map epistatic interactions between mtDNA and nuclear genomes and quantify genetic variation for the maintenance of uniparental mtDNA inheritance (Jeff Adrion). We are also investigating the consequences of this coevolution for the evolution of the genes involved in mitochondrial-nuclear interactions.

Evolutionary genetics of energetics

Energetic traits, such as ATP levels, must be maintained as organisms adapt to different ecologies and dynamically respond to variable environments within their lifetime. These energetic traits also underlie basic processes of cell division, growth and development. We are increasingly interested in the genes and physiologies that link temperature to metabolic rates and growth rates in insects (Luke Hoekstra). How do the pathways underlying largely homeostatic and conserved physiological systems nevertheless harbor variation within populations, diverge among populations and evolve across phylogenies?

Modeling physiological performance as a function of biochemical flux

Physiology informs us about the biology that links genotypes and phenotypes. We are using equations that describe biochemical flux through pathways to develop modeling approaches that connect genetic to phenotypic variation.

Montooth, KL, Meiklejohn, CD,Abt, DN and DM Rand (2010) Mitochondrial-nuclear epistasis affects fitness within species but does not contribute to fixed incompatibilities between species of Drosophila.Evolution64(12):3364-3379
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